Toyota 4AGE Reliability

[tonyc]

I just had to replace a crankshaft in my Toyota motor due to a crack in the number four rod journal. I don't know most of the motor's history, but it supposedly had 3 hours on it since the last rebuild. Now I also know there are a ton of variables (redline previously used, total hours on the crank, cold starting procedures, etc etc.) and this was a "used" motor so I willingly took my chances and this is in no way a witch-hunt.

What I would like to know, having had little experience with the Toyota Atlantic motors, is whatever anyone can tell me about reliability. Aside from the basic need of any race motor (good oil feed, cooling, rev limits vs. engine life, etc,), are they as reliable or unreliable as the Cosworth BDA? Do they have certain problem areas? What should I watch out for that is particular to Toyotas?

Thanks in advance.
Tony

[Paul LeCain]

What kind of car is it in? DB-4s are very oil sensitive.

You can run them 1100-1200 miles with a 9600-9800 rev limit. If you use more, like 10,200-10,400, then I'd get it rebuilt at 800-900 miles.

I've never had any kind of crank failure as long as the engine had oil. I've got one crank that's at least 12 years old. It's a TRD crank that has been ground .010 under.

[Stan Clayton]

Tony, if your engine has a TRD FA crank in it that is the first one I have heard of cracking, and some are more than 15 years old. OTOH, if it has a OEM crank then it is something to expect from extended running above 9500 RPM, according to a couple of guys I know who build(t) their own engines.

Other than that the principal weakness I know of is that the head castings are pretty thin in places, and aggressively ported heads have a history of cracking between the water jacket and the exhaust port.

Since you are replacing the crank, be sure to spec a TRD crank.

Stan

[GregoryJ]

I've got 5 1/2 hrs documented with my first injected 4AGE with no significant leakdown changes, no drop in performance and no issues whatsoever. I shift at about 10k but have had it up to 10,900 and had a few zingers when a dog ring let me down. I change the oil after every race and test day and clean the air filter, that's about the extent of the engine maintenance. I've schedule 5 more races and a test day before the end of the season at which time the engine will come out.

Regards,
GregoryJ

[Rick Ross]

I researched this subject prior to purchasing my DB4, and the general consensus was that the engines should be good for around 1200 miles if using a max rpm of 9600. Higher rpm's obviously would lead to less time between rebuilds. I was also told that valves, pistons, and con rods were more likely to fail than the crankshaft. Don't know how accurate this info is......just passing along the advice of others who have experience operating and/or building these engines.

Paul --- what oil quantity would you recommend for the DB4? I have emptied the oil tank, oil cooler, and oil filter. Soon it will be time to re-fill the tank and run the motor. Any advice would be appreciated.

Rick

[tonyc]

Guys,

Thanks sso much for the help. To answer some of your questions, my engine builder thinks it looks like a Doug Kidde crank, but he's not sure. I did spec out a TRD crank, and plan to use a 9600-9800 redline. The motor is in a 93H Reynard and the oil system seems to be designed very well with a large tank having a centrally mounted pickup. The pump was pumping 100psi cold which didnt drop to less than 80psi runnung (I though this seemed high but didn't make any changes).

All in all, you guys have given me some good news. I'll keep an eye on the rest of the stuff.
Thanks
tc

[Paul LeCain]

Rick,

We checked it two ways.

As I remember the first - in the front part of the oil tank there's a cast shelf you can see if you look down through the swirl tank. Set the 'warm' oil level to 3/8" above that shelf. You should run the engine, shut it off and check immediately.

Then, after every run, there should be a couple ounces of oil in the overflow catch tank. Just replace that oil. If there isn't any, add 4-8 oz. until there is some in the overflow.

[Rick Ross]

Paul,

Thank you. Do you remember approximately how much oil you added to the DB4 tank after an engine change and/or maintenance? Just curous what the approximate total capacity of the system is (tank, cooler, filter, lines, etc.).

Rick

[RussMcB]

Rick, this isn't DB-4 specific, but may work for you.

Recently when I filled my completely empty, unknown capacity system, I filled the oil tank about 90-95%. I was also able to add a quart into my engine's sump (to help prime the scavenge pump). Then I removed spark plugs and cranked the engine while watching the oil pressure and looking down into the oil tank. After a few seconds of cranking I could see oil entering the tank. I made a guess about where the level should be - High enough to get max capacity but not so high it will end up pumping much into the catch can.

I think this is a relatively safe method, especially if you check it frequently. Luckily, with dry sump systems the only repercussion of over filling is pumping excess oil into the catch can.

[GregoryJ]

Paul --- what oil quantity would you recommend for the DB4? I have emptied the oil tank, oil cooler, and oil filter. Soon it will be time to re-fill the tank and run the motor. Any advice would be appreciated.

Rick

My DB-4 takes only 4qts if you just drain the tank and 5.5 if you pump the cooler and lines dry. I don't use a conventional oil filter which would probably add a quart or so. I also keep adding a bit of oil between sessions and it always finds its level.

[Jim Gustafson]

Rick:
In my DB-4 we check the oil level just as Paul indicates in his post. In my car it takes approx 10 qts to get to that level, after we've had the engine out. We always want to make sure we puke out a few ounces, which is the best indicator that the system has what it needs to keep the engine from going in to cardiac arrest.
Jim

[Steve O'Hara]

Greg,

Something isn't right. My DB4 takes 9.5 quarts to bring the warm level to 1/4" above the shelf. At that level it maintains a very consistent 85 to 90 psi oil pressure even in very warm weather and on the long banked turns 1&2 at California Speedway. It loses very little, maybe an ounce in 30 miles, to the catch tank each session.
Sounds to me like you are way low on the oil level in your car.
Regards,
Steve O'hara

[GregoryJ]

Steve
You're not the first person who's told me that but the oil is right up where it belongs and that is using those quantities I mentioned. Perhaps running a standard oil filter and the extra length of oil line that requires adds more capacity to the system. When the engine was first put in we added closer to the amount you mentioned but it simply won't take that much oil just draining the tank. On two occassions I've second guessed myself and tried to add the extra quart only to have it fill up the catch can shortly after start up. What am I missing here?